Automatically deployable and retractable rear ladder, particularly for emergency vehicles

Abstract

A two-rail rear ladder system that automatically deploys and retracts a ladder from a vehicle, such as an emergency vehicle. The ladder is deployable and retractable with minimal or no human intervention, thereby saving time and/or creating less risk for injury. The ladder is deployed from the rear of a vehicle and rests at an angle on the ground when fully deployed. A two-stage drive unit system is used to deploy and retract the ladder. One drive unit deploys and retracts the ladder on a first rail to a position where the ladder tilts towards the ground. The second drive unit deploys and retracts the ladder from the tilted position to and from the ground on a second rail. Only a partial portion of the ladder's length is required to be deployed before the ladder will tilt downward towards the ground thereby minimizing open space needed behind the vehicle to deploy the ladder.

1 . A two-rail vehicle ladder deployment and retraction device, comprising: 
 a ladder comprising a plurality of steps, wherein the ladder is coupled to a ladder rail, and wherein a ladder drive unit is attached to the ladder and controls the traversal of the ladder along the ladder rail; and    a carriage coupled to a roof rail mounted on a roof of the vehicle, wherein a carriage drive unit is coupled to the carriage to control the traversal of the carriage along the roof rail;    wherein during a first deployment stage, the carriage drive unit moves the carriage to move the ladder rail from a storage position towards the rear of the vehicle and tilts the ladder rail downward towards the ground; and    wherein during a second deployment stage, the ladder drive unit moves the ladder downward along the ladder rail towards the ground.    
   
   
       2 . The device of  claim 1 , further comprising a ladder-roof rail coupler to the ladder rail, wherein the carriage drive unit causes the ladder and ladder rail to traverse along the roof rail when the ladder-roof rail is engaged in the roof rail.  
   
   
       3 . The device of  claim 2 , wherein during the first deployment stage, the carriage drive unit tilts the ladder rail downward by partially disengaging the ladder-roof rail coupler from the roof rail.  
   
   
       4 . The device of  claim 2 , 
 wherein during a first retraction stage, the ladder drive unit moves the ladder upward along the ladder rail towards the roof of the vehicle; and    wherein during a second retraction stage, the carriage drive unit moves the carriage to retract the ladder rail and the ladder to a storage position towards the front of the vehicle.    
   
   
       5 . The device of  claim 1 , further comprising a ladder-roof rail coupler attached to the ladder rail, wherein the carriage drive unit causes the ladder and ladder rail to traverse along the roof rail when the ladder-roof rail is engaged in the roof rail.  
   
   
       6 . The device of  claim 4 , wherein during the first retraction stage, the ladder-roof rail coupler is partially engaged with the roof rail to engage the ladder-roof rail coupler to the roof rail.  
   
   
       7 . The device of  claim 1 , wherein the ladder is comprised of a top section and a bottom section attached to the top section using a hinge, wherein the bottom section is adapted to flip up onto and rest on the top section to shorten the length of the ladder when stored.  
   
   
       8 . The device of  claim 1 , further comprising a ladder screw shaft that couples the ladder drive unit to the ladder to control the traversal of the ladder along the ladder rail.  
   
   
       9 . The device of  claim 1 , further comprising a carriage screw shaft that couples the carriage drive unit to the carriage to control the traversal of the carriage along the roof rail.  
   
   
       10 . The device of  claim 9 , further comprising a second carriage screw shaft that couples the carriage drive unit to the carriage, wherein the carriage drive unit drives the carriage screw shaft and the second carriage screw shaft to control the traversal of the carriage along the roof rail.  
   
   
       11 . The device of  claim 1 , wherein the carriage contains one or more carriage rollers that are coupled inside the roof rail such that the one or more carriage rollers roll inside the roof rail when the carriage traverses the roof rail.  
   
   
       12 . The device of  claim 1 , wherein the ladder contains one or more ladder rollers that are coupled inside the ladder rail such that the one or more ladder rollers roll inside the ladder rail when the ladder traverses the ladder rail.  
   
   
       13 . The device of  claim 2 , wherein the ladder-roof rail coupler contains ladder-roof rail coupler rollers that are coupled inside the roof rail such that the ladder-roof rail coupler rollers roll inside the roof rail when the ladder-roof rail coupler is fully engaged with the roof rail.  
   
   
       14 . The device of  claim 13 , wherein the roof rail contains a roof rail slot that is adapted to release the ladder-roof rail coupler roller to partially release the ladder-roof rail coupler from the roof rail to tilt the ladder rail towards the ground when the ladder-roof rail coupler roller is located in the roof rail slot.  
   
   
       15 . The device of  claim 1 , further comprising handrails that are coupled to the ladder.  
   
   
       16 . The device of  claim 15 , further comprising handrail posts hingedly attached to the ladder via handrail post hinges, wherein the handrails are supported by the handrail posts, and wherein the handrails are adapted to be folded down onto the ladder about the handrail post hinges.  
   
   
       17 . The device of  claim 1 , further comprising a secondary roof rail attached to the roof of the vehicle and located between the front of the vehicle and the roof rail, wherein the secondary roof rail is adapted to receive and support the ladder when stored.  
   
   
       18 . The device of  claim 8 , wherein the ladder drive unit is coupled to the ladder screw shaft to cause the ladder screw shaft to rotate via a sprocket and chain system.  
   
   
       19 . The device of  claim 2 , further comprising at least one strut fixedly attached to the ladder-roof rail coupler, wherein the at least one strut stops the ladder-roof rail coupler from tilting further downward towards the ground after being partially disengaged from the roof rail.  
   
   
       20 . The device of  claim 19 , wherein the at least one strut is fixedly attached to the carriage on its end opposite of attachment to the ladder-roof rail coupler.  
   
   
       21 . The device of  claim 7 , wherein the bottom section contains two aligned orifices on each side of the bottom section, and further comprising a handle lock attached to a dead bolt that is coupled to one of the two aligned orifices when the handle lock is unlocked and is coupled to both of the two aligned orifices when the handle lock is locked to prevent the bottom portion from moving about the hinge.  
   
   
       22 . The device of  claim 16 , wherein the handrail posts contains orifices that are aligned with each other in a direction parallel to the ladder rail, and further comprising a handle lock attached to a dead bolt that is coupled to a subset of the aligned orifices when the handle is unlocked and is coupled to all of the aligned orifices when the handle lock is locked to prevent one or more of the handrail posts from moving about the handrail post hinge to keep the handrail posts upright.  
   
   
       23 . A method for deploying and retracting a ladder from a vehicle, comprising: 
 driving a carriage during a first deployment stage using a carriage drive unit to drive a ladder rail supporting the ladder away from the front of the vehicle along a roof rail mounted on the roof of the vehicle until the ladder tilts downward towards the ground;    driving the ladder from the ladder rail towards the ground during a second deployment stage using a ladder drive unit.    
   
   
       24 . The method of  claim 23 , wherein driving the carriage further comprises driving a ladder-roof rail coupler attached to the ladder rail, wherein the ladder-roof rail is coupled to the roof rail during the first deployment stage.  
   
   
       25 . The method of  claim 24 , further comprising disengaging the ladder-roof rail coupler from the roof rail before the step of driving the ladder during the second deployment stage.  
   
   
       26 . The method of  claim 23 , 
 driving the ladder during a first retraction stage using the ladder drive unit up along the ladder rail; and    driving the carriage using the carriage drive unit during a second retraction stage towards the front of the vehicle and along to the roof rail that is mounted on the roof of the vehicle, until the ladder reaches a storage position.    
   
   
       27 . The method of  claim 26 , wherein driving the carriage during a second retraction stage further comprises driving a ladder-roof rail coupler attached to the ladder rail.  
   
   
       28 . The method of  claim 27 , further comprising engaging the ladder-roof rail coupler to the roof rail before the step of driving the carriage during the second retraction stage.  
   
   
       29 . The method of  claim 26  further comprising flipping up a bottom section of the ladder onto and resting on a top section of the ladder to shorten the length of the ladder when stored before driving the ladder in the first retraction stage.  
   
   
       30 . The method of  claim 23 , wherein driving the carriage during the first deployment stage further comprises driving a carriage screw shaft that couples the carriage drive unit to the carriage to control the traversal of the carriage along the roof rail.  
   
   
       31 . The method of  claim 26 , wherein driving the ladder during the second deployment stage further comprises driving a ladder screw shaft that couples the ladder drive unit to the ladder to control the traversal of the ladder along the ladder rail.  
   
   
       32 . The method of  claim 26 , wherein driving the ladder during the first retraction stage further comprises driving a ladder screw shaft that couples the ladder drive unit to the ladder to control the traversal of the ladder along the ladder rail.  
   
   
       33 . The method of  claim 26 , wherein driving the carriage during the second retraction stage further comprises driving a carriage screw shaft that couples the carriage drive unit to the carriage to control the traversal of the carriage along the roof rail.  
   
   
       34 . The method of  claim 23 , further comprising storing a portion of the ladder on a secondary roof rail attached to the roof of the vehicle and located between the front of the vehicle and the roof rail.  
   
   
       35 . The method of  claim 24 , wherein driving the carriage during a first deployment stage further comprises the carriage driving a strut fixedly attached to the carriage and the ladder-roof rail coupler to tilt the ladder downward towards the ground.  
   
   
       36 . The method of  claim 26 , wherein driving the carriage during a second retraction stage further comprises the carriage pulling a strut fixedly attached to the carriage and the ladder-roof rail coupler to tilt the ladder upward to a position parallel to the roof rail.  
   
   
       37 . The method of  claim 29 , further comprising unlocking a handle attached to the bottom section of the ladder before flipping up the bottom section.  
   
   
       38 . The method of  claim 23 , further comprising lifting up a handrail hingedly attached to the ladder after driving the carriage in a second deployment stage.  
   
   
       39 . The method of  claim 26 , further comprising pushing down a handrail hingedly attached to the ladder before driving the ladder in the first retraction stage.  
   
   
       40 . The method of  claim 39 , further comprising unlocking a handle attached to the handrail before pushing down the handrail.